It is the long range purpose of this project to study the control mechanisms important in regulating protein synthesis in normal and malignant mammalian cells. A. Transcription of and translation by transfer RNA (tRNA) is being studied by comparing isoaccepting tRNA chromatographic profiles of normal tissues and tumors. tRNA from normal organs of mice and rats, primarily liver and brain, is being compared with tRNA from many different spontaneous and rat hepatomas. Of special interest is the origin, structure and function of tumor specific phenylalanyl-tRNA found only in certain mouse and rat tumors. B. The synthesis and structure of IgA half molecules, mouse IgA myeloma proteins made up of one light chain disulfide bonded to one unusually short heavy chain, is also of major interest, particularly to determine if these molecules represent a normal IgA subclass or products of aberrant or incomplete synthesis at the DNA, RNA or protein synthetic level. BIBLIOGRAPHIC REFERENCE: J. Frederic Mushinski and Miranda M. Dungan: IgA Half molecules. II. Genetic variants of IgA detected in normal mouse intestinal contents. J. Immunol., 117: 1668-1675, 1976.